Synthesis of new amidino-substituted 2-aminothiophenoles: mild basic ring opening of benzothiazole

Synthesis and Antioxidative Potency of Novel Amidino Substituted Benzimidazole and Benzothiazole Derivatives

“…[19] Synthesis of 4-amidinium-1,2-phenylenediamine 11a and 2-(3,4-diaminophenyl)-4,5-dihydro-1H-imidazol-3-ium chloride 11b were carried out according to the literature. [20] General method for the synthesis of benzothiazole derivatives 3-10 A mixture of the corresponding aldehyde 1a-1d (0.5 mmol) and 2-amino-5-amidiniumbenzenethiolate 2a (0.5 mmol) or 2-amino-5-(4,5-dihydro-1H-imidazol-3-ium-2-yl)benzenethiolate hydrate 2b (0.5 mmol) in glacial acetic acid (5 mL) was stirred at reflux under nitrogen for 3 h, followed by the addition of concentrated hydrochloric acid (0.5 mL) and additionally stirred at room temperature for 1 h. After cooling overnight, the crude product was filtered off, washed with acetone and crystallized to obtain pure compounds 3-10.…”

“…Recently, we found glacial acetic acid to be an efficient solvent for direct condensation of aldehydes and amidino substituted 2-aminothiophenoles giving rise to the corresponding 2-substituted-6-amidinobenzothiazolyl compounds in high yield without the need of any catalyst or oxidant. [24] Consequently, cyclocondensation of 2-amino-5-amidiniumbenzenethiolate 2a [19] and 2-amino-5-(4,5 -dihydro -1H -imidazol -3 -ium -2 -yl)-benzenethiolate 2b [19] with commercially available aldehydes 1a-1d in refluxing acetic acid followed by quenching with hydrochloric acid afforded targeted cationic 6-amidino-2-arylbenzothiazole compounds which were isolated as hydrochloride salts. The zwitterionic precursor 2a and 2b were prepared by Pinner reaction from 6- cynobenzothiazole according to our previously developed method.…”

“…The zwitterionic precursor 2a and 2b were prepared by Pinner reaction from 6- cynobenzothiazole according to our previously developed method. [19] Amidino and 2-imidazolinyl substituted benzimidazole derivatives 12-19 were obtained according to the experimental procedure shown in the Scheme 2. Starting from previously prepared 4-amidino/4-(2-imidazolinyl)-1,2-phenylenediamines hydrochlorides 11a and 11b, [20] due to the cyclocondensation with corresponding benzaldehydes 1a-1d in absolute ethanol and by using with p-benzoquinone as oxidizing reagent, 2-phenylbenzimidazole derivatives bearing amidino substituents 12-19 were prepared as hydrochloride salts.…”

Hydrogen and halogen bonding patterns and π–π aromatic interactions of some 6,7-disubstituted 1,3-benzothiazoles studied by X-ray diffraction and DFT calculations

“…As a continuation of our recent studies on synthesis [17,18], antitumor activities [19,20], structural and computational investigations [21][22][23] of substituted benzothiazoles, in this paper we report CAHÁ Á ÁO/N/Br and NAHÁ Á ÁO/N/S hydrogen bonds, CAClÁ Á ÁO and CAIÁ Á ÁO/N halogen bonds, BrÁ Á ÁBr dihalogen interactions and p-p interactions of 6-chloro-7-nitro-bta (3), 6-iodo-7-nitro-bta (5), 6-amino-7-iodo-bta (6), 6-acetylamino-7-iodo-bta (7), and 6-amino-7-bromo-bta (8) studied by X-ray crystal structure analysis. DFT calculations were also performed for obtaining minimum energy and determination of possible hydrogen and halogen bonding sites of studied disubstituted benzothiazoles.…”

Novel amidino substituted 2-phenylbenzothiazoles: Synthesis, antitumor evaluation in vitro and acute toxicity testing in vivo

“…21 The 5-amidinium-2-aminobenzothiolate 8a and 5-(imidazolinium-2-yl)-2-aminobenzothiolate hydrate 8b were prepared according to the literature. 23 4.1.1. Synthesis; general procedures (i) Condensation reaction of corresponding 6-substituted-2-aminothiophenole with 4-substituted benzoylchloride: To a solution of corresponding 6-substituted-2-aminothiophenole (1.1 equiv) in glacial acetic acid 4-substituted-benzoylchloride (1.0 equiv) was added in one portion and the reaction mixture was refluxed under nitrogen for 4 h. After cooling to rt, the resulting precipitate was collected by filtration, washed with diethyl ether and dried under vacuum over KOH.…”